Regenerative air preheater with stationary heat retaining mass and revolving connections



J. KOCH 3 7 REGENERATIVE AIR PREHEATER WITH STATIONARY HEAT RETAINING MASS AND REVOLVING CONNECTIONS Filed Nov. 7. 1962 Aug. 31, 1965 4 Sheets-Sheet 1 INVENTOR },#/44

014 ,4; ATTORNEY Aug. 31, 1965 J. KOCH 3,203,471

REGENERATIVE AIR PREHEATER WITH STATIONARY HEAT RETAINING MASS AND REVOLVING CONNECTIONS Filed Nov. 7, 1962 4 Sheets-Sheet 2 INVENTOR Aug. 31, 1965 J. KOCH 3,203,471

REGENERATIVE A PREHEATER WITH STATIONARY HEAT RETAINING S AND REVOLVING CONNECTIONS 7 Filed Nov. 7, 1962 4 Sheets-Sheet 3 Fig.10

INVENTOR ATToRNE 3,203,471 NARY HEAT RETAINING CTIONS 4 Sheets-Sheet 4 J. KOC 'I'ER WITH S REVOLVING Aug. 31, 1965 REGENERATIVE AIR PRE MASS A Filed NOV. 7, 1962 INVENTOR ALATTORNQ United States Patent 3,203,471 REGENERATIVE AIR PREHEATER WITH STA- TIONARY HEAT RETAINING MASS AND REVOLVING CONNECTIONS Jakob Koch, Edingen, near Heidelberg, Germany, assignor go Sflvenska Rotor Maskiner Alrtieholag, Stockholm,

we en Filed Nov. 7, 1962, Ser. No. 236,062 3 Claims. (Cl. 1654) This invention relates to a regenerative air preheater having a stationary heat retaining mass divided into sector shaped compartments and revolving fluid channel communications.

According to the invention the heat retaining mass is separated into two superimposed heat retaining stages spaced from each other in the direction of fluid flow and in the annular space between said stages a rotary disk valve is provided synchronously rotating in phase with the revolving fluid channel communications and divided cross sectionally into sector shaped compartments corresponding to those of the revolving fluid channel communications. Thus the rotary slide valve within the free annular space forms continuations of the channels formed by the revolving fluid channel communications.

Conveniently a minor phase displacement may be applied to the slide valve and possibly also to one of the fluid communications, for instance in connection with a withdrawal off of the sluiced air.

There are several possibilities in constructing such a rotary slide as will be apparent from the following description. By means of a multistage regenerative air preheater the heating of the air and reversely the cooling down of the flue gases is effected in stages. Generally two such equal or different heat retaining stages are sufficient, although under particular circumstances a further subdivision into more than two succeeding equal or different heat retaining stages of course may be provided.

Since in such a multi-divided preheater the conditions in reality are equivalent, it will be suflicient to describe the invention by virtue of a number of two-stage air preheaters.

In order to illustrate the inventive idea, for this reason eight different embodiments are shown in the drawings of such two-stage air preheaters and more precisely in cross sections in a plane through the axis of rotation and/or in cross sections perpendicular to the axis of rotation.

Since the most essential elements are recurrent in all these embodiments, all the reciprocal details have been denoted by the same reference numeral in all the examples even if they in the separate case may be designed differently in accordance with the modified construction.

In the drawings:

FIGS. 1 and 2 show the first example of embodiment.

FIGS. 3 and 4 show the second example of embodiment.

FIGS. 5 and 6 show the third example of embodiment.

FIG. 7 shows the fourth example of embodiment.

FIGS. 8 and 9 show the fifth example of embodiment.

FIG. 10 shows the sixth example of embodiment.

FIGS. 11. and 12 show the seventh example of embodiment.

FIG. 13 shows the eighth example of embodiment.

As is evident from the axial section of the first example shown in FIG. 1 the heat retaining mass is divided in two heat retaining stages 1 and 2 which are superimposed in the fluid flow direction. Both heat retaining stages are located at a distance from each other so that an annular space 3 is provided therebetween. The air channel 4 provides a revolving inlet communication 4 and an outlet communication 4" is also provided. Coaxially there- 3,203,471 Patented Aug. 31, 1965 with the flue gas channel 5 is provided and more precisely includes stationary inlet and outlet communications 5 and 5". In the examples of construction it is assumed that the flue gas and the air flow are in counterflow relative to each other-as shown by the arrows-through both the channels. In a similar manner the parallel flow principle of course is also possible, but in practice the same is not commonly used.

The communications 5' and 5" for the flue gas are stationary and extend into the cylindrical shell of the air preheater. Rotary conections are in this case only necessary for the air channel and more precisely the inlet and outlet communications 4' and 4" lead to segmentally formed slide valves 6 and 6" which are attached to the rotary shaft 7 and revolve inside the flue gas channels 5 so as to delimit a revolving segmental section for the air flow through the heat retaining mass.

In the free annular space between the heat retaining mass stages 1 and 2 a rotary segmentally shaped rotary slide valve 8 is fastened to the shaft 7 which slide valve rotates synchronously and in phase with the connection communications 6. and 6", and in certain degree provides a continuation thereof through the annular space 3. This rotary slide valve is not packed with a heat retaining mass and only forms the intermediary member bordering the air channel along its sectional passageway. However, it is to be noted that the reverse constructional arrangement also may be chosen, so that the air channel represents the outer conduit and the flue gas channel the inner conduit having revolving connections.

Said arrangement of the heat retaining mass into two superimposed stages of heat absorbent material further enables inlet and outlet connections of a partial flue to the annular space 3. The connection to said space 3 may be provided externally or internally. In the embodiment according to FIGS. 1 and 2 and also as shown In FIGS. 3 and 4 a connection is provided externally and more precisely a jacket 9 for this purpose encircles the jacket shell 10 of the rotary slide valve 8 to provide an annular hollow space 11. To this hollow space 11 either the flue gas channel as shown in FIGS. 1 and 2 or the air channel as shown in FIGS. 3 and 4 is interconnected.

In the embodiment according to FIGS. 1 and 2 there is also shown the flue gas channel 5 connected with the annular channel 11 and more precisely with a portion of the annular space 3 which is uncovered by the rotary slide valve 8. The air channel 4 through the annular space 3 is closed externally by the unbroken jacket shell 10 and internally by a corresponding jacket shell 10, and on both the radial sides by radially disposed walls 12 and 13 to close the intermediate annular space 3 between the stages 1 and 2 and in sealing engagement on both the sides of the air channel in FIG. 2 the sealing plates 14 and 15 are shown.

The air preheater according to FIGS. 1 and 2 shows further the utilization of the two-stage air preheater for high air temperatures in which the hot air preheater stage 1 is provided with a feed water heater or an evaporator 16 connected in parallel and disposed in the flow path of a partial flue gas stream which thereafter flows into the annular space 3. However, it is also possible by means of the same construction such as shown in FIGS. 1 and 2 to admit flue gases in a completely arbitrary manner into the annular space 3 or to discharge said flue gases from this space.

According to the embodiment illustrated in FIGS. 3 and 4 the mode of operation is reversed and more precisely so that the rotary slide valve 8 does not close the air channel within the space 3 but instead closes the flue gas channel 5. Instead the air channel is connected with the annular channel 11, while the flue gas channel 5 is closed on all side-s by means of the bordering walls 10,

a 12, 13 and 10 of the rotary slide valve 8 so that said air channel is closed and led through the annular space 3 as shown in FIG. 4. By means of such an arrangement additional air could further be supplied between both the air preheater stages to flow through the heat retaining stage 1 together with the air which already has passed through the stage 2. Of primary interest is the reversed construction shown in FIG. 3, since from the annular space 3 air is exhausted which already "has been moderately heated, so as for example to be used in coal mills while the remaining air passes through stage 1 and therein is brought to a corresponding higher temperature.

The diflerence between this example of embodiment and the first one above-described is particularly evident from FIG. 4, which also shows the preheater in a vertical section through the axis of rotation. Here particularly the varied form of the rotary slide valve 8 is shown. In this form the included angle between the radial bordening walls 12 and 13 is the same as in FIG. 2, but the external jacket 10 encircles the flue gas channel instead of the air channel.

According to the example of embodiment shown in FIGS. and 6 a partial flue gas stream is supplied to the annular space 3 having previously passed through the feed water heater or evaporator 16 connected in parallel with the hot stage 1. It is, however, to be kept in mind that the radial separating walls 18 of both the heat retaining stages 1 and 2 uninterruptedly pass through the annular space 3. By means of such arrangement the necessary sealings in the construction described above between the front ends of the rotary slide valve 8 and the opposing end faces of both the heat retaining stages 1 and 2 may be dispensed with. The rotary slide valve 8 is of smaller radial dimensions in relation to the above constructions and seals ofi. mainly by its external jacket shell relative to the inner edges 17 of the radial separating walls 18. Within the heat retaining stages 1 and 2 the edges 17 of the radial separating walls 18 abut against concentric jacket shells 19 and 20, respectively, the inner cylindrical spaces of which are not packed with heat retaining material but instead is free or receives with the feed water heater 16.

The example of embodiment according to FIG. 7 discloses generally the same construction, but here a feed water heater 16 is removed from the space enclosed by the cylindrical jacket shell 19 and located in a place more easily accessible. For this purpose the flue gas partial flow supplied to the feed water heater 16 is fed through a stationary channel 21 and a rotating channel 22 connected thereto is led through the stationary air channel 4" and the rotating channel communication 6".

In the air preheater according to FIGS. 8 and 9 a moderately heated partial air stream is exhausted immediately following the cool preheater stage 2 to bypass the hot preheater stage 1 and flow in axial direction through the middle portion as well as through the upper rotating communication 6" and the stationary air channel 4 by means of the channels 23 and 24. By way of distinction from the example of construction according to FIG. 7 the rotary slide valve 8 by means of its sealing segment 10 covers a portion of the preheater communicating with the flue gases.

A further variation of the last mentioned air preheater construction is shown in FIG. 10. In this example of construction a partial stream is divided off from the entering air stream which partial stream is led in axial direction through a central inlet opening 25 from the inner part of the preheater stage 2 into the annular intermediate space 3, where said partial stream mingles to a certain ex tent with the moderately heated primary air stream in the stage 2 and passes from the preheater. This arrangement shows in effect a by-pass on the air side of the preheater.

Even if the hitherto described rotary slide valves 8 are to be regarded as segmental portions of a cylinder the same effect may be obtained if instead of such a segment a complete cylindrical rotor is substituted which by means of radial separating walls incorporated therein serves as the just described rotary valve. In order to provide the desired admission or exhaust of the partial air stream or the partial gas stream, respectively, in such a construction it is, however, necessary to omit completely a portion of the exterior rotary valve shell or provide the same with perforated passage openings.

Another form of construction of the rotary valve is shown in FIGS. 11 and 12 which differs from the original rotary valve construction described above in that the same only utilizes a cut out section of the rotary valve shell. Here the hot preheater stage 1 is of a somewhat smaller diameter than the cool air preheater stage 2. Furthermore the preheater stage 1 has its own exterior jacket shell 26 spaced from the llue gas channel 5 encircling the same. Around the jacket shell is disposed the rotary valve shell 27, which is firmly attached to the rotary valve connection 6" and covers the edges 17 of the radial separating walls 18, which also here run through the whole height of the air preheater without interruption in the annular space 3 between the stages 1 and 2. Since the rotary valve shell 27 revolves together synchronously and in phase with both the rotary valve connections 6 and 6", the air stream in the annular space 3 between the heat retaining stages 1 and 2 and each of two radial separating walls 18 as Well as the shaft 7 will be closed relative the flue gas by the valve shell 27.

In the construction according to FIGS. 11 and 12 the air stream from admission to discharge from the air preheater as regards its quantity remains unchanged, while a partial flue gas stream is admitted to the main flue gas stream through the anular channel 11. In a corresponding manner from this annular channel 11 a partial line gas stream may also be discharged. From other points of view, however, it is possible to let the flue gas stream, as regards its quantity, to pass unchanged through both the air preheater stages, and to withdraw a partial stream from the air stream via the annular channel 11 or to supply a partial stream thereto. In this case only the shell 27 has to be modified and more precisely in such a manner as is shown in the horizontal section perpendicular to the axis of rotation and, furthermore, taken in a plane through the intermediate space 3 in FIG. 13.

As is clear from the examples already shown, several other combinations of the disclosed characteristics of the invention are possible. What is, essential is as may be indicated from the above examples of embodiment, that the intermediate annular space 3, free from any heat retaining mass and for admission and discharge, respectively, of a partial stream includes a rotary valve which within the space 3 provides a continuation of the rotary channel connections at the ends and thereby provides a closed passage-way for one of the two heat exchange fluid media, and more precisely, particularly the medium to which no partial stream is supplied or from which no such partial stream is discharged, but also in certain cases for the other medium, as by Way of example, in air preheaters with more than two stages.

What is claimed is:

1. A regenerative air preheater having a stationary heat retaining mass divided into sector-shaped compartments, inlet and outlet means communicating with said compartments for flow of a heat exchanging fluid therethrough, revolving second inlet and outlet means providing sequential communication with said compartments for flow of a second heat exchanging fluid therethrough, said heat retaining mass being separated into two superimposed heat retaining stages spaced from each other in the direction of fluid flow to provide an annular space therebetween, a rotary slide valve disposed in said annular space between said stages, means to synchronously rotate said valve in phase with said revolving second inlet and outlet means,

said valve being divided cross sectionally into sectorshaped passages in alignment with said revolving second inlet and outlet means, whereby said passages provide continuations in said annular space of said revolving second inlet and outlet means.

2. A regenerative air preheater as defined in claim 1, in which an annular chamber encloses said rotary slide valve and in which said rotary slide valve is provided with an external jacket shell open to an extent corresponding to one of said slide valve passages, whereby said one passage communicates with said annular chamber to provide for flow of fluid thereto.

3. A regenerative air preheater as defined in claim 1, in which a central channel passes axially through said References Cited by the Examiner UNITED STATES PATENTS 3,077,926 2/63 Fikenscher 165-7 CHARLES SUKALO, Primary Examiner.

ROBERT A. OLEARY, Examiner. 

1. A REGENERATIVE AIR PREHEATER HAVING A STATIONARY HEAT RETAINING MASS DIVIDED INTO SECTOR-SHAPED COMPARTMENTS, INLET AND OUTLET MEANS COMMUNICATING WITH SAID COMPARTMENTS FOR FLOW OF A HEAT EXCHANGING FLUID THERETHROUGH, REVOLVING SECOND INLET AND OUTLET MEANS PROVIDING SEQUENTIAL COMMUNICATION WITH SAID COMPARTMENTS FOR FLOW OF A SECOND HEAT EXCHANGING FLUID THERETHROUGH, SAID HEAT RETAINING MASS BEING SEPARATED INTO TWO SUPERIMPOSED HEAT RETAINING STAGES SPACED FROM EACH OTHER IN THE DIRECTION OF FLUID FLOW TO PROVIDE AN ANNULAR SPACE THEREBETWEEN, A ROTARY SLIDE VALVE DISPOSED IN SAID ANNULAR SPACE BETWEEN SAID STAGES, MEANS TO SYNCHRONOUSLY ROTATE SAID VALVE IN PHASE WITH SAID REVOLVING SECOND INLET AND OUTLET MEANS, SAID VALVE BEING DIVIDED CROSS SECTIONALLY INTO SECTORSHAPED PASSAGES IN ALIGNMENT WITH SAID REVOLVING SECOND INLET AND OUTLET MEANS, WHEREBY SAID PASSAGES PROVIDE CONTINUATION IN SAID ANNULAR SPACE OF SAID REVOLVING SECOND INLET AND OUTLET MEANS. 